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Green technique to make freshwater from wastewater

Researchers have developed an eco-friendly technique that uses a specific solution and a thin-film membrane to extract freshwater from industrial wastewater, seawater and brackish water1. This technique offers a way to overcome scarcity of freshwater needed for industry and agriculture.

Freshwater reserves are steadily depleting across the globe, pushing researchers to devise ways to make freshwater by treating wastewater and desalinating seawater. Existing techniques for treating various kinds of wastewater are complex and expensive.

Scientists from the CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat, led by Kamalesh Prasad, invented a green forward-osmosis process that employs a specific solution made of organic compounds and a thin-film membrane. They then explored its potential to make freshwater from brackish water, seawater, dye-contaminated wastewater and tannery wastewater.

This technique was able to extract 90% reusable freshwater from dye-contaminated wastewater, seawater and dirtiest tannery wastewater. It helped treat the tannery wastewater, reducing liquid waste considerably.

The technique uses a solution that exhibits low toxicity and remains effective throughout multiple water recovery cycles. This solution helps extract reusable water from wastewater more efficiently than the other tested ionic liquids. “Besides making reusable water from contaminated wastewater, this technique takes us a step closer to achieving zero liquid waste disposal targets,” says Prasad.



  1. Mahto, A. et al. Sustainable water reclamation from different feed streams by forward osmosis process using deep eutectic solvents as reusable draw solution. Ind. Eng. Chem. Res. 56, 14623-14632 (2017)

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